Deformation of a Dental Ceramic following Adhesive Cementation

2009 ◽  
Vol 89 (1) ◽  
pp. 87-90 ◽  
Author(s):  
G. Isgró ◽  
O. Addison ◽  
G.J.P. Fleming
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Alumina Particle ◽  
Polished Surface ◽  
Air Abrasion ◽  
Hybrid Layer ◽  
Surface Imperfections ◽  
Resin Coating ◽  
Adhesive Cementation ◽  
Induced Changes

Stress-induced changes imparted in a ‘dentin-bonded-crown’ material during sintering, annealing, pre-cementation surface modification, and resin coating have been visualized by profilometry. The hypothesis tested was that operative techniques modify the stressing pattern throughout the material thickness. We polished the upper surfaces of 10 ceramic discs to remove surface imperfections before using a contact profilometer (40-nm resolution) to measure the ‘flatness’. Discs were re-profiled after annealing and after alumina particle air-abrasion and resin-coating of the ‘fit’ surface. Polished surfaces were convex, with a mean deflection of 8.4 ± 1.5 μm. Mean deflection was significantly reduced (P = 0.029) following alumina particle air-abrasion and increased (P < 0.001) on resin-coating. Polishing induced a tensile stress state, resulting in surface convexity. Alumina particle air-abrasion reduced the relative tensile stress state of the contralateral polished surface. Resin-polymerization generated compression within the resin-ceramic ‘hybrid layer’ and tension in the polished surface and is likely to contribute to the strengthening of ceramics by resin-based cements.

Determination of the Biaxial Anisotropy Coefficient Using a Single Layer Sheet Metal Compression Test

2021 ◽  
Vol 883 ◽  
pp. 303-308
Author(s):  
Peter Hetz ◽  
Matthias Lenzen ◽  
Martin Kraus ◽  
Marion Merklein
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Sheet Metal ◽  
Compression Test ◽  
Test Procedure ◽  
Rolling Direction ◽  
Single Layer ◽  
Material Behavior ◽  
Biaxial Tensile ◽  
Biaxial Tensile Stress

Numerical process design leads to cost and time savings in sheet metal forming processes. Therefore, a modeling of the material behavior is required to map the flow properties of sheet metal. For the identification of current yield criteria, the yield strength and the hardening behavior as well as the Lankford coefficients are taken into account. By considering the anisotropy as a function of rolling direction and stress state, the prediction quality of anisotropic materials is improved by a more accurate modeling of the yield locus curve. According to the current state of the art, the layer compression test is used to determine the corresponding Lankford coefficient for the biaxial tensile stress state. However, the test setup and the test procedure is quite challenging compared to other tests for the material characterization. Due to this, the test is only of limited suitability if only the Lankford coefficient has to be determined. In this contribution, a simplified test is presented. It is a reduction of the layer compression test to one single sheet layer. So the Lankford coefficient for the biaxial tensile stress state can be analyzed with a significantly lower test effort. The results prove the applicability of the proposed test for an easy and time efficient characterization of the biaxial Lankford coefficient.

scholarly journals Failure analysis of the rubber track of a tracked transporter

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878952 ◽  
Author(s):  
Weiwei Liu ◽  
Kai Cheng ◽  
Jun Wang
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Failure Analysis ◽  
Test Site ◽  
Strength Theory ◽  
Cycle Index ◽  
Soil Stress ◽  
Machinery Building ◽  
Simple Stress ◽  
Working Hour

Rubber-tracked transporters are becoming increasingly popular in agriculture, forestry and military transportation. Rubber track systems are typically fitted instead of using tyres on the transporter to decrease soil stress and increase trafficability. Therefore, the accurate failure analysis of a rubber track is important. A model for predicting stress distribution along a rubber track is presented in this study. In the model, the stress along a rubber track consists of the vertical stress below the rubber track, tensile stress, bending stress and centrifugal tensile stress. Moreover, fourth strength theory was used to change a complicated stress state to a simple stress state. An experiment was performed at the test site of Harbin First Machinery Building Group Ltd, with a total weight of 61.789 kN. The experiment was conducted to verify and approve the theoretical model. The Miner rule was used to predict the cycle index and working hour of the rubber track, thereby providing a method for predicting the fatigue life of a rubber track.

The Characteristics of the Magnetic Memory Signals under Different States for Q235 Defect Samples

2010 ◽  
Vol 97-101 ◽  
pp. 500-503 ◽  
Author(s):  
Jian Wei Li ◽  
Min Qiang Xu ◽  
Jian Cheng Leng ◽  
Ming Xiu Xu
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Magnetic Behavior ◽  
Ferromagnetic Materials ◽  
Magnetic Memory ◽  
Testing Environment ◽  
Memory Signals ◽  
Stress States ◽  
Testing Environments ◽  
Different Characteristics

Magnetic behavior of ferromagnetic materials has been using to detect defects of materials. To evaluate the stress states of the components by the magnetic memory signal, Q235 defect asymmetrical samples were made. The characteristics of magnetic memory of Q235 have been studied in the three different testing environments which are online-loading, online-unloading and offline-unloading under cycle tensile stress. The results show that magnetic memory signals have different characteristics in different testing environment. It is feasible to evaluate preliminarily the stress state by the magnetic memory signals.

Seismic Affection Analysis of Weir Dam Based on 3-D FEM

2013 ◽  
Vol 438-439 ◽  
pp. 1546-1550
Author(s):  
Jin Chao Yue ◽  
Xiao Bin Zhang ◽  
Ling Min Ye
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Seismic Action ◽  
Earthquake Excitation ◽  
Principal Tensile Stress ◽  
Radial Gate

The vibrant-type-disintegration method is applied to calculate structure seismic action of a weir dam. Based on calculation and analysis of the weir dam, special attention is paid to the stress state of key parts. The results show that the displacement and stress of weir dam are affected by earthquake excitation direction. Since large principal tensile stress appears in the joint of girder and pier, and the zone of principal tensile stress is large because of the thrust of radial gate and steep changes of geometry shape, we should pay special attention when calculating anti-seismic checking and reinforcement arrangement.

Two-Parameter Parabolic Mohr Strength Criterion Applied to Analyze the Results of the Brazilian Test

2014 ◽  
Vol 624 ◽  
pp. 630-634 ◽  
Author(s):  
Qi Fan ◽  
Shuan Cheng Gu ◽  
Bo Nan Wang ◽  
Rong Bin Huang
Keyword(s):  
Tensile Strength ◽  
Stress State ◽  
Tensile Stress ◽  
Failure Modes ◽  
Strength Criterion ◽  
Complex Stress State ◽  
Brazilian Test ◽  
Practical Significance ◽  
Uniaxial Tensile ◽  
Two Parameter

Geotechnical engineering in tension damage is one of the major failure modes. For a long time, Brazil test has practical significance and wide application value that has been used to determine the tensile strength of rock. When the specimen center destroyed tensile stress play a major role that is the theoretical basis of Brazil test. This is uniaxial tensile stress state, but the reality is complex stress state. Theoretical analysis shows that the Brazilian test does not truly reflect the tensile strength of rock, its test results to error. In this paper, two-parameter parabolic Mohr strength criterion for this error analysis, and propose amendments to the formula.

scholarly journals Development of Microstructures with Improved Cryogenic Toughness Through Local Variations in Stress State: Aluminum-Lithium Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
K. T. Venkateswara Rao ◽  
R. O. Ritchie
Keyword(s):  
Stress State ◽  
Sheet Material ◽  
Thin Sheet ◽  
Local Stress ◽  
Cryogenic Temperatures ◽  
Aluminum Lithium ◽  
Thin Sheet Material ◽  
Local Stress State ◽  
Crack Tip Constraint ◽  
Induced Changes

AbstractMicrostructurally-induced changes in the local stress state (triaxial constraint) and their effect on fracture-toughness behavior are examined at ambient and cryogenic temperatures in an Al-Li-Cu-Zr alloy, processed in the form of 12.7 mm-thick "naturally laminated" plate containing aligned-weak interfaces and 1.6 mm-thin unlaminated sheet. It is shown that marked improvements in long-transverse (L-T) toughness can be achieved in the plate material at cryogenic temperatures by promoting through-thickness delamination along these interfaces, which relaxes local constraint and promotes a fracture-mode transition from global plane strain to local plane stress. Conversely, in thin sheet material, the absence of such interface delamination leads to a reduction in toughness with decrease in temperature, consistent with the greater degree of crack-tip constraint.

Damage zone development in PVC under a multiaxial tensile stress state

1991 ◽  
Vol 26 (19) ◽  
pp. 5374-5382 ◽  
Author(s):  
A. Tse ◽  
E. Shin ◽  
A. Hiltner ◽  
E. Baer
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Damage Zone ◽  
Zone Development
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